A kitchen table at 11pm, a printer feeding a letter, an envelope and a stamp beside it.

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What is a letter before action, and how do I write one?

The short answer

A formal last letter. It comes before a court claim, and the court's rules say the person making the claim writes it1: you don't need a solicitor. A company usually gets 14 days1 to answer, a sole trader 30 days2. Skip it and the court can cut your interest or make you pay costs1, even if you win.

Mara, WolfX research desk
Written with AI, checked by a person · 8 October 2026

England and Wales only. WolfX is software, not a law firm.

The numbers

How long to give them, and what a claim costs.

14 daysTime a company gets to answer, in a simple case.1

30 daysTime a sole trader gets, counted from the date at the top of the letter.2

£35–£455Court fee to start a claim for up to £10,000, set by the amount claimed.8

What you can add

A £7,500 invoice, 75 days late

Say you invoiced another business £7,500, due on 31 July 2026. On 14 October 2026 it is still unpaid: 75 days late, after two reminders that went unanswered. Interest started on 1 August 2026, so it uses the rate fixed on 30 June: 8%5 over a Bank Rate of 3.75%6, which is 11.75% a year. You write the letter on 14 October and give the company until 28 October 2026.

£7,500.00The invoice

£181.08Interest: £7,500 × 11.75% ÷ 365 × 75 days3

£70.00Fixed sum (invoices from £1,000 to £9,999.99)4

£7,751.08Owed on 14 October 2026

Then it grows by £2.41 a day until they pay. If the date in your letter passes, a court claim for this sum costs a £455 court fee8, and you may be able to claim the fee back if you win8.

The road ahead

Seven steps. One court fee, only if needed.

Step 1: Check who you are writing to
Companies House shows11 a company's registered office and any insolvency information, so search the name there first. A limited company gets the letter below. A sole trader is an individual, so the Pre-Action Protocol for Debt Claims2 applies and step 4 is yours.
Cost: FreeTime: 5 minutes
Step 2: Work out the sum
Add the invoice, interest and the fixed sum as at the date of the letter. For an invoice that went late from 1 July to 31 December 2026, interest is 11.75% a year6. Interest to the day, step by step.
Cost: FreeTime: 10 minutes
Step 3: Fill in the letter and date it
The court's pre-action rules ask for1 the basis of your claim, the facts, what you want and how the sum is worked out. The letter has all four and offers to talk1, as the court expects. Enclose copies of the invoice and your order or contract.
Cost: FreeTime: 15 minutes
Step 4: Sole trader? Add the pack
The protocol2 calls this letter a Letter of Claim and asks for more. Enclose an up-to-date statement of account, the Information Sheet and Reply Form (Annex 1) and a Financial Statement form (Annex 2), both in the protocol.
Give 30 days, and say where to send the Reply Form back. If the deal was spoken, say who agreed what, when and where. Skip this step for a limited company.
Cost: FreeTime: 20 minutes
Step 5: Send it twice, and keep proof
Post it to the registered office10 and email it to the person who approves payments. A sole trader's letter goes by post2 on the day it is dated or the next, with email as the extra. Keep the letter, proof of posting and sent email together.
Cost: A stampTime: Same day
Step 6: Wait for the date
A company has 14 days1 in a simple case. That is the court's yardstick, not a hard deadline, and a claim started before the date can count against you. A reply should say whether the claim is accepted and, if not, why. A sole trader's 30 days are in step 4.
Cost: FreeTime: 14 or 30 days
Step 7: Still unpaid? Start the claim
Make it to the county court9, online or by post. Scotland and Northern Ireland use a different process. The fee8 is set by the sum plus interest. A sole trader who replied but did not settle should get 14 days' notice2 first.
Cost: £455 court fee in the exampleTime: Under an hour

A letter you can copy

Letter before action to a limited company

Send it to a limited company once your reminders have failed. Sole trader? Follow steps 4 and 5, and the notes below.

New email

SubjectLetter before action: invoice , unpaid

By post and by email Dear , Letter before action: invoice I supplied to your company, as agreed. Invoice , for , was due on . It has not been paid. Under the Late Payment of Commercial Debts (Interest) Act 1998, interest and a fixed sum are also due. As at the date of this letter: Invoice: Interest at a year, from the day after the due date: Fixed sum for late payment: Total owed: Interest is still running at a day. Please add it for each day after the date of this letter until you pay. Please pay the total by to: If it is not paid by then, I will start a claim in the County Court and ask for the court fee and further interest as well. I would rather settle this without a court. If you want to talk it through, or think mediation would help, reply to me at the details below. If you believe any of this is wrong, please tell me before that date and say why. Copies of the invoice and of the order or contract are enclosed. Yours sincerely,

Tap a highlighted gap to see what goes in it.

Post it to the registered office on the date it carries, and email a copy to the person who approves payments. Keep the letter, the proof of posting and the sent email together. Sole trader: put their name and address at the top, write 'you' for 'your company', set the pay-by date 30 days on, and post it that day or the next with the pack from step 4. Add a line giving the address for the Reply Form. Keep the claim line only if you will start the claim. If your contract sets its own interest rate, use that instead of the Act line.

When not to bother

When it isn't worth it

Your customer is a member of the public. The interest and fixed sum only cover sales between businesses3. Consumer debts have their own rules, which this page does not cover.
The company is in administration or liquidation. In administration, legal process needs the administrator's consent or the court's permission12. Tell whoever is running it what you are owed instead.
They dispute the invoice and your paperwork is thin. Ask what is disputed and why, in writing, and ask for the undisputed part first. For a large or tangled sum, a solicitor who does debt recovery is worth an hour.
The sum is small and the client is worth keeping. A claim for £500 or less costs £35 or £50 to start8, at least a tenth of it, and a formal letter can cost you the client. Ring first, and send the letter if the call changes nothing.
It is nearly six years old. Six years7 is the limit, and the letter does not stop the clock1. Start the claim first, then ask the court to pause it.

The Wolf's note

Write it for two readers: the person who approves payments, and a judge who may see it later. The judge will look for the facts, the sum and an offer to talk. Send it, keep the proof, and let the date run.

Mr. Wolf · the AI inside WolfX

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